顾及周期项误差和起点偏差修正的北斗卫星钟差预报

根据北斗卫星导航系统星载原子钟自身的物理特性,采用武汉大学IGS数据中心发布的2016年1月1日至2016年11月1日共306天的事后钟差产品进行谱分析。分析结果表明:北斗卫星导航系统的3类卫星钟都存在一定的周期特性;其中GEO和IGSO卫星钟的主周期相对较为明显;GEO卫星钟的主周期依次为12、24、8和6h;IGSO的主周期为24、12、8和6h;而MEO的3个主周期为12.9、6.4和24h。依据各类原子钟的周期特性,同时对各天之间钟差的起始点偏差进行修正,并利用修正模型对北斗卫星钟差进行预报和精度分析。试验结果表明,改进的预报模型能显著提升北斗卫星的钟差预报精度,北斗卫星钟差24h、12h、6h的平均预报精度分别能达到6.55ns、3.17ns和1.76ns。

The Prediction of BeiDou Satellite Clock Bias Based on Periodic Term and Starting Point Deviation Correction

According to the physical characteristics of the BDS on-board atomic clocks, a spectral analysis method is used to detect the periodicity based on the products published by the IGS data Center of Wuhan University from January 1, 2016 to November 1, 2016.The results show that there are periodic fluctuations in the three types of satellite clocks.The main period of GEO and IGSO satellite clock bias is relatively obvious.The testing with nearly a year data showed that the main periods of GEO are 12, 24, 8 and 6h, but for IGSO are 24, 12, 8 and 6h, while those for MEO are 12.9, 6.4 and 24h.Based on the periodic characteristics of different types of clocks and the correction of the starting point deviation of the clock bias, a modified prediction method of satellite clock bias is used to forecast the BeiDou satellite clock bias.The results show that the modified method can significantly improve the prediction accuracy, the 24h, 12h, 6h average forecast accuracy can reach 6.55ns, 3.17ns and 1.76ns respectively.